In recent years the economics of farming have made efficient farm management critical. Soil erosion and chemical runoff have led farmers to adopt various precision farming techniques, including conservation tillage. Further soil characteristics and environmental conditions have a direct impact on crop yield. Specifically, soil compaction can have a direct negative effect on crop yields. Regions of high mechanical resistance in the soil may arise as natural soil features, be caused by heavy farm machinery or by the formation of plow pans. Compacted soils with high strength reduce growth rates of crop roots and thus limit the acquisition of water and nutrients to the plant. This may affect crop yield. Different soil tillage practices are thus implemented to reduce soil compaction.
Advances in site-specific crop management (precision agriculture) provide capabilities to vary soil treatment across an agricultural field. Soil tillage is one of them. Although, conventional methods of crop management provide similar impact across the entire field, different parent material, topography and past management can cause significant variability of soil compaction. Therefore, local (spot) or variable depth tillage may increase efficiency of this field operation. By avoiding tillage of soil with a relatively low level of compaction, both economical and environmental improvements of crop production can be achieved through: 1) reduction of energy waste, and 2) preserving developed soil structure.
Soil compaction is related to several physical and mechanical characteristics and is defined specifically as the volume change produced by momentary load application caused by rolling, tamping or vibration. Measurement of mechanical resistance of soil to a penetrating object is recognized as a conventional method to estimate soil strength at a given point. The American Society of Agricultural Engineers have specified a penetrometer with a conical tip as the standard method to determine a soil strength index from a static penetration test.
Even if automated, cone penetrometer measurements are time consuming and highly variable. On-the-go measurements of soil mechanical resistance, however, allow for a substantial increase in measurement density. A number of prototype systems have been developed to map soil mechanical resistance on-the-go. Some have been used to determine horizontal soil resistance at a particular depth; others have been developed to quantify different operation parameters associated with implement draft performance. These systems allow mapping spatial variability of soil resistance; however, multiple depth measurements are needed to prescribe variable depth tillage. Other prototype systems have been developed to determine both spatial and depth variation of soil resistance or use an instrumented subsoiler to map “hard-pans” through a dynamic operation of the implement. The resulting maps could be used to prescribe variable depth tillage in different field areas. A control system can then be used to guide tillage equipment at appropriate depth.
Accordingly, there is a clear need in the art for an instrumentation system based on a commercial implement for deep soil tillage that can identify changes of soil mechanical resistance with depth and guide itself to appropriate operation depth in real-time.